BACKGROUND: Serum gamma-glutamyltransferase (GGT) has been suggested as a predictor for development of the metabolic syndrome in non-Korean population, but studies in Korean population are scarce. Therefore, we examined the association between serum GGT levels and the incidence of the metabolic syndrome in Korean male office workers. METHODS: The study population consisted of 32,692 office workers who underwent health checkups in both 2005 and 2009. A total of 17,583 with elevated GGT levels, the presence of metabolic syndrome, medication history at baseline, and female office workers were excluded. Finally, 15,109 subjects were included in the final analysis. We measured serum GGT levels and individual metabolic components. RESULTS: As a quartile of serum GGT increased, 4-year follow-up incidence of the metabolic syndrome increased. After adjustment for age, alcohol drinking status and smoking status in 2005, logistic regression analysis showed that the odds ratios (95% confidence interval) for incident metabolic syndrome in 2009 compared to the lowest quartile and upper quartiles were 1.00 (reference), 1.57 (1.24-2.00), 2.73 (2.17-3.43), 3.78 (3.02-4.74), and statistically significant (P < 0.001), respectively. CONCLUSION: These results showed that the higher serum GGT predicted the future development of metabolic syndrome. In Korean male office workers without the metabolic syndrome, the serum GGT levels despite normal levels were associated with an increased risk of incident metabolic syndrome.